• tComment - gcc to comment a line, gcp to comment blocks, nuff said
• rails.vim - syntax highlighting, gf (goto file) enhancements, and lots more. should be required for any rails dev
• rake.vim - like rails.vim but for non-rails projects. makes :Rtags and other commands just work
• ruby.vim - lots of general enhancements for ruby dev
• necomplcache - intelligent and fast complete as you type, and added Command-Space to select a completion (same as Ctrl-N)
• snipMate - offers textmate-like snippet expansion + snippets collection (honza/vim-snippets). Try hitting TAB after typing a snippet
• jasmine.vim - support for jasmine javascript unit testing, including snippets for it, before, etc..
• vim-javascript-syntax, vim-jquery - better highlighting
• TagHighlight - highlights class names and method names
• vim-coffeescript - support for coffeescript, highlighting
• vim-stylus - support for stylus css language
• vim-bundler - work with bundled gems
• fugitive - “a git wrapper so awesome, it should be illegal…”. Try :Gstatus and hit - to toggle files in and out of the index. Git d to see a diff. Use git mergetool or gmt to launch vim as a mergetool. The left buffer is your branch, the right is the incoming change, and in the middle is the working copy. Move to the left or right and use dp to put the change into the middle. Learn more: http://vimcasts.org/blog/2011/05/the-fugitive-series/
• gv.vim - use :GV for a better git log browser